Final answer:
The primary somatosensory cortex is located in the parietal lobe's postcentral gyrus, and it is responsible for processing tactile sensations such as touch and pressure, as well as body position and movement. Sensitivity and nerve density in different body areas are represented in the size of the corresponding region within the sensory homunculus in the somatosensory cortex.
Step-by-step explanation:
The primary sensory cortex responsible for the perception of touch is located in the parietal lobe of the brain. More specifically, this region is known as the postcentral gyrus, which lies immediately posterior to the central sulcus. Within this area of the brain, tactile senses such as touch, pressure, tickle, pain, itch, and vibration are processed, along with proprioception and kinesthesia, which relate to body position and movement. The postcentral gyrus is also referred to by Brodmann's areas 1, 2, and 3. The considerably complex processing of these somatic senses involves the relay and integration of information to produce a coherent sensory experience.
When it comes to the sensory homunculus, which is a visual representation of the body within the brain that maps out the cortical area devoted to each body region, certain parts have larger representations than others. This phenomenon reflects the density of sensory receptors in different parts of the body. The size of representation within the somatosensory cortex for a specific body part correlates to the sensitivity and number of nerve endings present in that area.